Telephone -system



H, E. CLAUSEN AND C. L. GOODRUM. TELEPHONE SYSTEM.

APPLICATION FILED SEPT. 14, 1917.

1 ,343 ,903 Patented June 22, 1920.

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ven fans: Hen/'y P [/danse/7 Char/&s L. Good/ um UITED STATES HENRY P. CLAUSEN, OF MOUNT VERNON, AND CHARLEE L. GOODRUM, OF NEW YORK IN'. Y., ASSIGNOBS TO WESTERN ELECTRC COUPANY, ILNCOEPORATED, 075' NEW YORK, N. Y., A COEPORATION OF NElV YORK. i

TELEPHONE SYSTEM.

essons.

This invention relates to telephone systens enploying electrically operated` switching apparatus for establishing connections between sub/scrbers lines.

lllore particularly it relates to a system enploying V directively actuated switching devices in which a plurality of terminal sections are arranged to be traversed by separate brush sets individual to each sec-` tion and carried by a connnonshaft, which is aetuated by a `single Operating inechanisin in response to one character of impulse series to position one set of brushes in position to coperate with its associated section, and in response to a different character of impulse series to position another set of brushes for operation with the section with which it is associated.

One oi" the objects is the pro'vision o' means, in connection with a selective switch o the foregoing character, whereby the pas icular set of brushes appropriated for use in extending a connection is electrically connected to the incoming or calling line.

in accordance with a feature ot' the invention said means includes a plurality of relays withcircuits therefor, associated with the switch Operating circuits in such a inanner as to respond directly to the impulses transnitted 'froni the calling substation to render effective one or another of the brush sets, dependentupon the number of impulses transmitted.

A clearer concepton o the nventon will he had froni a consideration of the 'followingdescription, taken in connection with the acconpauying drawing wherein the figure diagraminatically illustrates so muchof a telephone system `as is necessary to an understanding of the said invention.

.ltefcrring to the drawing, 1 represents a subscriber s substation having a calling transinitter by means of which the neces- Speofication of Letters Patent.

Patonted J une 22, 1920.

i Application filed September 14, 1917. Serial No. 191356.

sary impulses :may be sent over the line to operate the central oiiice switching apparatus n conpletng a telephone connection' with another Subscriber. At 3 is shown the line or stepping relay of the selector switch, the circuit of which relay is repeatedly opened and closed each tine the impulse sender 2 is nianipulated. The selector brush shaft 4; has fasten'ed thereon the two sets of brushes 5, 6, 7' and 8, 9, 10. Brushes 5, 6, 7 are arranged to wipe over the contact terminals of all trunk groups in the lowersection of the bank, which, as will later appear, are the even digit groups; and brushes 8, 9, 10 are arranged to make contact with all the groups located in the upper or odd digit section of the bank. ln the figure only two groups of terminals and a portion of another group are shown to each section. However, it will be understood that in practice several such groups would be provided, the oinission being made merely for convenience in the representation of the figure.

Shaft l is pr rided wita a racl( ll having on one side thereoi?, a series of closely spaced ratchet teeth 12, and on its ,other side a series of more distantly spaced ratchet teeth 13. A priinary or group selecting magnet PM has an armature 14, pivoted at 15, and which is provided at its free end With a stepping pawl 16. Upon each energization of magnet .PM the consequent attracton of* armature ll causes the pawl 16 to engage one of the teeth 13 to elevate the hrush shait through one long step. For this purpose armature l-l is nade conparatively long; in order to pernii't of a suii'iciently wide range of motion for pawl 16. Considering the position assuined by the brushes during each of these successivo long steps of the shatt l, it is to 'be understood that the ratchct teeth 13 are so spaced on the rack ll that when one impulse ill'FtYQl' es primar; magnet PM and pawl 16 is actuatcd to give shutt one long step, the brushes 8, 9, 10 are brought into operative position below the first group ot truni; terminals in the uppcr section of the bank. i l/'hen two inipulses are delivered to magnet PM and the shatt talres two long steps, the brushes 5, (3, 7 are positioned in operative relation to the first group of tcrininals in the lower section oi the bank. lt three inipulses are sent the brushes 8, 9, 10 are operatively positioned with respect to the second terminal group in the' upper section. And if four impulses are sent, brushes, 6, 7 are positioned below the second group in the lower section. In a similar manner, for as many groups as 'may be contained in each section, an Odd number of impulses operates to place brushes 8, 9, 10 below the corresponding group in the Odd section, while an even number of impulses operates to position brushes 5, 6, 7 below the corresponding group in the even section. In accordance with the above described operation of the switch shaft and its associated brushes,and assuming for example the switch shown is one of a number of selectors in a 1000 line exchange, all groups of trunks having access through succeeding connectors to lines with telephone numbers having an odd first digit are arranged in the upper section or" the selector bank. On the other-hand, all trunk groups representing lines with aneven first digit number are arranged in the lower section.

A secondary stepping magnet SM has an armature 17 pivoted at 18, and provided at its free end witha pawl 19. For each impulse traversing magnet SM armature 17 is attracted and thereby moves the pawl 19 into engagement- 'with one of the closely spaced ratehet teeth 12 to move the shaft one short or trunk hunting step. For each short step thus taken the particular set ot brushes that was previously positioned below a group of terminals is moved up over the successivo terminals in such group in search of an idle trunk. A pair of interrupter springs 20 and 21 is normally held in a circuit closin'g position by armature l?, but upon the attraction of said armature, springs 20 and 21 are opened to nterrupt a circuit y 'or the secondary magnet as will later appear.

A pawl 22 is pivoted to the free end of armature and normally rests in engagement with the ratehet teeth 12 to maintain shaft 4 in its actuated position. Armature 'TO is controlled by a release magnet RM, which upon energizing attraets the same to withdraw the holding pawl, thereby allowing the brush shaft to restore to its normal position. Relays 23 and 24 are each composed of two windings. 'Said relays are wound so that the magnetzing efiect of one long and short step principlc. However, it is to be understood that the said invention, which consists in the provision of means 'tor the selection of one or another of a plurality of simultaneously actuated sets of brushes, according as the conditions require, is not limited to the particular type ot switch shown.

Having explained in general the elements comprising the illustrated cmbodiment, a

more detailed description will now be given of the process involved in extending a call from a substation through the selector switch shown.

Consider that the subscriber at substation l desires to communicate with some other subscriber having a telephone number the first digit of which is an odd number, as tor instance the digit 5. By removing the receiver from the hook a circuit is completed to start an idle finder or other preliminarv switch in operation. Such switch, being well understood, is not shown in the figure. The preliminary switch upon making connection with the tcrminals of the calling line extends the same over the trunk 26, to close a circuit tor line relay 3 of the selcctor switch. This circuit nay be followed from free pole of battery, left-hand winding oi" relay 3,first position contact and side-switch arm 27, trunk conductor 25, through the preliminary switch, over the loop of substation l, back through the preliminary switch, trunk conductor 26, side-switch arm 28 and its first position contact, right-hand winding of relay 3, to ground. Relay 3 by attracting its armature closes the following circuit: ground, side-switch arm 29 and its first position contact, armature and front contact ot relay 3, conductor 30, winding of slow-to-rclease relay 31, to battery and ground.

The energization of relay 3 also establishcs the following circuit for the left-hand winding of differential relay 23: ground, sideswitch arm 29 and its first position contact, armature and front contact of relay 3, conductor 32, outer left-hand armature and contaot of the diferential relay 24-, left-hand winding of relay 23, to battery and ground. Relay 23 energizes in this circuit to attract its armatures, and thereby closes a looking circuit for itself as follows: free pole of battery, left-hand winding, contact and letthand armature of relay 23, conductor 33, to ground at the right-hand armature and contact of slow-to-release relay 31.

The calling Subscriber now opcratcs the sender 2 to transmit a series of impulses corresponding to the first digit of the dcsired number, or as assumed. five impulses. At the first opening of the line by sender 2. relay 3 retracts its armature to close a circuit for a second slow-to-release relay 34, traceable from ground side-switch arm 29 and its first position contact, armature and back contact of relay 3, conductor 35,1eft-hand armature and front contact of relay 31, winding of relay 34, to battery and ground. Relay 34 attracts its armature to establish a circuit for the escape magnet 36, from ground, armature and contact of relay 34, first position contact and side-switch arm 37, winding of magnet 36 to battery. The escape magnet controls the side switch and is designed to step the same from first to second positions by denergizng. It will be noted that the circuit of relay 31 is opened by the retraction of the line relay armature, but being slow to release it holds its armature, and thereby maintains the previously traced locking circuit for the differental relay 23 during the short interval relay 3 'is denergized. Another circuit is established by the retraction of the line relay s armature, traceable from ground, side-switch arm 29 and its first position contact, armature and back contact of relay 3, conductor 35, left-hand armature and front contact of relay 31, conductor 38, first position contact and side-switch arm 39, winding of the primary stepping magnet PM, to battery and ground. magnet by energzing gives the shaft 4 one long step and places brushes 8, 9, 10 below the first group in the upper section of the bank.

Still another circuit is completed by the denergization of the relay 3 in response to the first interruption of the line. This circuit leads from greund, side-switch arm 29 and its first position contact, armature andvback contact of relay 3, conductors 35 and 40, outer right-hand armature and front contact of relay 23, left-hand winding of relay 24, to battery and ground. Relay 24 energizes in this circuit and attracts its armatures. Thereupon a holding circuit is completed for said relay as follows: battery, left-hand winding, contact and inner left-hand armature of relay 24, conductor 33 to ground at the right-hand armature and contact of relay 31. As soon as the line is again closed by sender 2 at the completion of the first impulse relay 3 attracts its armature to close a circuit from ground, side-switch arm 29 and its first position contact, armature and front contact of relay 3, conductor 32, outer lefthand armature and front contact of relay 24, contact and inner right-hand armature of relay 23, right-hand winding of relay 23, to battery and ground. Current flowing in this winding of relay 23 neutralizes the effect of the other winding, thereby permitting the armatures to retract, ?which in turn severs the circuits of both of said windings. Thus at the end of the first impulse of the group selecting series, we find that one Operating impulse has been delivered to the primary circuit to place brushes 8, 9, 10 below the first terminal group in the Odd Said stepping i group section, and that the condition of differential relays` 23 and 24 is as follows: The circuits of both windings of relay 23 are open and therefore the armatures are in their retracted position.. The left-hand winding of relay 24 is energized and its circuit locked as above explained. Hence the armatures of this relay are in their attracted position.

The second opening of the line, immediately following the first, causes line relay 3 to denergize and release its armature as before. This sends a second Operating impulse to primary magnet PM over the previously traced circuit. Another crcuit is also completed at the same time from ground, side switch arm 29 and its first position contact, armature and back contact of relay 3, concluctors 35 and 40, outer right-hand armature and back contact of relay 23, contact and innermost right-hand armature of relay '24, right-hand winding of relay 24 to battery and ground. Current flowing in this winding of relay 24 neutralizes the nagnetizaton of the lefthand winding and the relay permits its armatures to retract to their normal positions. As soon as-the line closes at the end of the second interruption by the sender, line relay 3 attracts its armature and the following circuit is completed: ground, side-switch arm 29 and its first position contact, armature and front contact of relay 3, conductor 32, outer left-hand armature and back contact of relay 24, left-hand winding of relay 23, to battery and ground. Relay 23 energizes in this circuit, attracts its armatures, and locks up over the previously traced circuit to ground at the right-hand armature and contact of slowto-release relay 31.

Two impulses of the group selecting series have now been sent with the result that magnet PM has given the shaft 4 two long steps to position brushes 5, (5, 7 below the first trunk group in the lower section of the bank. As to relays 23 and 24, we find that their condition is the same as when the relay 3 first energized at the time the selector switch was taken for use by the initiation of the call. That is, both windings of relay 24 are in open circuit, while relay 23 has its armature attracted due to the energization of its lefthand winding. Therefore, when the third opening and closure of the subscriber s line occurs for the purpose of sending the third impulse the operation of relays 23 and 24 is precisely the same as that resulting from the first opening and.closure. Said third impulse operates to energize magnet PM as before, whereby shaft 4 positions brushes S, 9, 10 below the second terminal group in the upper section. By analogy to the foregoing it is apparent that an odd number of impulses sent out by the calling subscriber serves to step brushes S, 9, 10 into operative relation to one of the groups in the upper section. And furthermore relays 23 and 24: respond directly to said odd numbered series of impulses so that at the cessation thereof relay' is-in its attracted condition. But if thesubscriber sends an even number of impulses, brushes 5, G, 7 are brought into operative relation to one of the groups in the lower section. And relays %and 24 respond directly to said impulses so that at the end thereof relay 241: is in its normal retracted condition.

In the case assume'chwhere the subscriber at station l wishes to converse with some other subscriber whose number'has 'live as its first digit, the transmission of the five impulses serves to move brushes 8, 9, 10 fire long steps and brings them to rest below the third group in the upper section, this being the fifth hundred group. ;An odd number of impulses having been sent relay 2% holds its armature-s attracted. This connects the conductors &l and 42 to the line brushes 9 and 10 respectively over the two outermost righthand armatures of relay 24. 4

Atthe termination or" the group selecting impulse series the line relay 3 holds its armature, causing an interruption in the circuit OI" relay 3& for a sutcient period to permit the latter to denergize. Relay 3 1- by r tracting its armature severs the escape magnet circuit and the side switch is stepped to second position. In this position a circuit is closed from ground, side switch arm 43 and its second position contact, interrupter springs 21 and 20, winding of the secondary stepping magnet SM, to battery and ground. Magnet SM interrupts its own circuit and steps the brushes 8, 9, 10 over the terminals of the selected group.

Idle trunks are those having a ground potential'on the test terminal thereot. Assume the trunk 4:4, l, 46 to be the first idle one encountered in the group. "When test brush 8 strikes the 'terminal of test conductor A, the 'following circuit is closed: grounded conductor 44, test brush S, conductor e?, front contact and next to the innermost right-hand armature of relay Qi, conductors 48 and &9, second position contact and side switch arin 37, escape magnet 36, to battery. Said escape magnet being so designed, steps the side switch into third position on energizing. This opens the circuit of magnet SM and stops the brusheson the idle trunk terminals. The calling line is now extended over side-switch wipers 27, 28, conductors 41, 42,'the two outermost right-hand armatures 'and front Contacts of relay 24, conductors 50, 51, brushes 9, 10, to the idle truni( conductors 45, &6, In any well known manner the idle ground may be removed from the trunk 44 by the operation of apparatus associated with the next succeeding switch in the system so that all multiples oi? said trunk will test busy to other selectors.

hen side-switch wipers 27 and 28 leave position 2, line relay 3 denergizes, and in turn causes relay 31 to retract its armatures. At its right-hand armature rclay 31 opens the above described holding circuit tor relay 24:. But the relay 31 being slow to release does not sever such circuit until after sideswitch arm 29 has arrived in its third position to substitute a new holding circuit i'or the relay 24:.

At the end of the Conversation and when the receivers are replaced, the idle ground potential again appears on the test conductor ai. A circuit may thereupon be traced from grounded conductor li, brush 8, conductor J, front contact and next to the innermost right-hand armature of relay 24:, conductor lS, third position contact and sideswitch arm 52, conductor 53, off-normal contacts and 58 winding of release magnet RM, to battery and ground. Magnet lil). attracts its armature 'TO to withdraw pawl :22 and allow the switch to restore to normal. irmature 23 also closes a looking circuit to insure a complete release of the brush shalt as follows: battery, winding of magnet RM. conducto' 56, oil-normal Contacts 58 and 57, Contacts 55% and 55, to ground.

Should the Subscriber at substation l desire to communicate with a subscribor whose number hasan even first digit, he scnds an even numbered series of group selecting impulses to step the brushes 5, (i, 'T below the corresponding terminal group in the lower section. In this case rol-ay El is in its normal retracted condition at the end of said impulses and conductors 4:1, 4:2 are therefore extended by way of conductors (SU to line brushes 6 and T respeetively.

lVhat is claimed is:

l. In a telephone system, a switch having a plurality of sets of brushes, a line, a plu rality of impulse circuits, a relay for sending impulses simultaneoi ly over each ot said crcuits, means for actuatin aid relay, means operated by the impulses sent over one of said ercuits i'or actuating said brushes, and means operated by the impulses sent over the other of said circnts 'for suecessively establishing and disestablishing a connection between said line and each of said sets of brushes.

2. In a telephone system, a seleetive switch having terminal groups, said groups being arranged in sets, a. plurality of sets of brushes, each one coperating with a dilien cnt set of said groups, a line, impulse circuits, a relay associated with said line i'or sending impulses simultaneously over said circuits, means for sending impulses over said line to actuate said relay, means operated by the impulses in one of said circui's for actuating said brushes, and means operated by the impulses in the other of said circuits 'or successively establishing and disestablishing a connection between said line and each of said sets of brushes.

3. In a telephone system, a Subscribers station, a selective switch having groups of terminals, said groups being arranged in sets, a plurality of sets of brushes, each one coperating with a different set of said groups, a plurality of impulse circuits, a relay for sending impulses over said circuits simultaneously, means for actuating said relay from the subscriber s station, means responsive to the impulses in one of said circuits for actuating said brushes, and means responsive to the impulses in the other of said circuits for successively rendering effective and inelfective each of said sets of brushes.

4. In a telephone system, a subscriber s station, a selective switch having terminal groups, said groups being arranged in sets, a plurality of brush sets, each one coperating with a different set of' said groups, impulse circuits, a'relay for sending series of impulses over said circuits, means for actuating said relay by impulses sent from the subscriber s station, means operated by the impulses in one of said circuits for actuating said brushes, and a plurality of relays operated by the impulses in the other impulse circuits for successively rendering effective and ineffective each of said sets of brushes.

5. In a telephone system, a Subscriber-s station, a selective switch having groups of terminals, said groups being arranged in two sections, a pair of brush sets in fixed relation with each other, one set for each section of terminal groups, impulse circuits, impulse mechansm in one of said circuits for moving said brushes over said terminal groups, a differential relay in the other of said circuits for successively rendering effective each set of brushes as such set is moved into operative relation to said groups, a relay for sending impulses over said circuits simultaneously, and means for actuating said last relay by impulses sent from the Subscribers station.

6. In a telephone system, a subscriber s station, a selective switch, two series of terminal groups for said switch, a. pair of sets of brushes coperating `therewith, one set for each series, impulse operated mechansm for moving said brushes simultaneously, means for sending impulses to said mechansm from the subscriber s station, and a diiferential relay directly responsive to said impulses ;for rendering effective each set of brushes as such set is moved into operative relation to the successive terminal 7. In a telephone system, a subscriber s station, a selective switch, series of groups of terminals for said switch, a plurality of sets of brushes in a fixed relation to each other, one set for each of said series of groups, impulse operated mechansm for moving said sets of brushes, means for sending impulses to said mechansm from the Subscribers station, and a differential relay directly responsive to said impulses for rendering each set of brushes effective as such set is moved into operative relation to the successive terminal groups.

8. In a telephone system, a Subscriber-s line, a selective switch having two series of terminals arranged in groups, a pair off sets of brushes coperating therewith, one set for each series, impulse Operating mechansm for moving said brushes simultaneously to select a desired one of said groups, means for sending impulses to said mechansm over the Subscribers line, and a differential relay responsive to said impulses for successivcly rendering effective each set ot brushes to extend saidsubscribefis line to the set of brushes having access to the selected group of terminals.

In witness whereof we hereunto subscribe our7names this Sth day of September, A. D., 191

HENRY i GLAUSEN. UHARLES L. GUODRUM. 

